1. Field of the Invention
The present invention relates to an absorbent article such as a sanitary napkin, a panti-liner or a disposable diaper and, more particularly, to an absorbent article which has little pressure but excellent fitness.
2. Related Art
In recent years, there have been many absorbent articles such as sanitary napkins, panti-liners, incontinence pads or disposable diapers for absorbing a discharged substance. Each of these absorbent articles is generally constructed to include: a liquid-permeable surface sheet to be directed to the wearer; a liquid-impermeable back sheet; and a liquid-absorbing layer sandwiched between the surface sheet and the back sheet. The surface sheet is brought into direct contact with the wearer""s skin so that it is preferred to provide a softer touch feel. Especially where the absorbent article is exemplified by the sanitary napkin, the surface sheet is a portion to receive the discharged liquid such as the menstrual blood directly from the vaginal opening. Therefore, the surface sheet has to enhance the contact with the vaginal opening thereby to prevent leakage of the liquid inbetween.
However, the shape of the portion near the vaginal opening of a woman is complicated and has large individual differences so that the sanitary napkin is difficult to be formed in advance into such a specific shape as to enhance the contact.
In a sanitary napkin developed in the prior art, therefore, a fine pattern of roughness is formed on the surface sheet, for example, as disclosed in Japanese Patent Laid-Open No. 200065/1993. In the surface sheet thus formed with the roughness pattern, however, the undulations are substantially identical in a substantially constant bulk so that the enhancement of the contact between the surface sheet and the vaginal opening is restricted.
As disclosed in International Patent Publication No. 512168/1998, on the other hand, there is a structure using a foam in an absorbent core. Generally speaking, however, the foam has a relatively high strength (in the compressive deflection) and a high repulsion so that the stimulation (e.g., resistance or load) to the wearer""s skin becomes increased thereby to raise a problem that a physical disorder is easily given to the wearer.
The present invention has an object to provide an absorbent article which is enabled to deform according to the shape of the private part of a wearer to thereby prevent leakage of a discharged liquid.
Another object of the invention is to provide an absorbent article which is so soft to the private part of a wearer as to contact gently with the skin.
According to an aspect of the invention, there is provided an absorbent article comprising: a support sheet; a liquid-absorbing layer disposed on the support sheet; and a liquid-permeable surface sheet covering the liquid-receiving face of the liquid-absorbing layer, wherein between the liquid-absorbing layer and the surface sheet, there is provided a liquid-permeable layer of crimped fibers which remain in a crimped state in a natural state without any external force, the crimped fiber layer being formed by interconnecting the crimped fibers to leave voids therebetween.
According to another aspect of the invention, there is provided an absorbent article comprising: a support sheet; a liquid-absorbing layer disposed on the support sheet; and a liquid-permeable surface sheet covering the liquid-receiving face of the liquid-absorbing layer, wherein the liquid-absorbing layer is formed of: a layer of crimped fibers which remain in a crimped state in a natural state without any external force, the crimped fiber layer being formed by interconnecting the crimped fibers to leave voids therebetween; and a liquid-absorbent material. In this structure, it is preferred that the liquid-absorbent material comprises at least one of liquid-absorbing fibers and an absorbent resin, and that the liquid-absorbent material is buried in the voids of the crimped fiber layer.
For example, the crimped fiber layer may be prepared by laminating a plurality of resin layers of different MFRs (melt flow rates) into a laminate film and by splitting the laminate film into a network.
Alternatively, the crimped fiber layer may be prepared by joining the crimped fibers at their intersections into a network.
Preferably, the crimped fibers are given such a sectional shape as has a larger width of 10 to 500 microns than a thickness of 10 to 100 microns and as has the maximum of a crimping external diameter of 0.3 to 20 mm in a free state without any external force.
Preferably, the crimped fiber layer has a shrinking tension of 50 mN or less for a width of 25 mm when the crimped fiber layer has a thickness of 3 to 30 mm and a tensile strain of 50% is applied in the longitudinal direction of the absorbent article only to the crimped fiber layer.
Preferably, a pushing load necessary for pushing the surface sheet by 5 mm is 150 mN or less for an area of 10 mm "PHgr" for the laminate of the liquid-absorbing layer, the liquid-permeable layer and the surface sheet. In this construction, it is preferred that the bulk recovery percentage of the pushed portion when the pushing force for 5 mm is released is no less than 40% and no more than 100%.
The liquid-permeable layer in the absorbent article of the invention is an aggregate of crimped fibers (or crimped filaments). If these crimped fibers are arranged to extend generally along the liquid-receiving face, the crimping external diameter thereof is directed generally in the height direction from the liquid-receiving face. The force necessary for tensing the crimped fibers in the fiber extending directions is so low that the restoring force (or the spring-back force) when the absorbent article is curved to the body shape is low. On the other hand, the crimped fibers have a remarkably low elastic modulus in the height direction from the liquid-receiving face, along which the crimping external diameter thereof is directed, so that the surface sheet can be easily deformed to conform to the shape of the private part of a wearer (e.g., the vaginal opening and therearound). Moreover, the elastic reaction for the deformation is so low that the pressure on the private part is accordingly low. Therefore, the absorbent article is excellent in the wearing feel and in the sealing performance.
Moreover, the crimped fibers have a function to guide the body liquid along the crimped portions from the surface sheet to the liquid-absorbing layer so that the body liquid having passed through the surface sheet can be quickly introduced into the liquid-absorbing layer.